JP3289922B2 - Ferroelectric liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

This invention comprises a ferroelectric liquid crystal medium, ie, one or more chiral dopes, between two plane-parallel plates with an electrode matrix of sampling electrodes and data electrodes perpendicular thereto. A ferroelectric liquid crystal display with improved multiplex performance, comprising a medium comprising a chiral component and a non-chiral substrate component comprising one or more non-chiral compounds.

[0002]

BACKGROUND OF THE INVENTION Ferroelectric liquid crystal displays typically include a liquid crystal medium having a chiral tilted smectic C phase (Sc *), which is obtained by doping an S _c substrate mixture chiral dopants ( W. Kussenski,
H. Stegmeyer, Chem. Phys. Lett. 70 (1983), 1
twenty three). These liquid crystal displays are described in Clark and Laguerre Wall (NA Clark and ST Laguerre Wall, Appl. Phys. Lett. 36 (1989), 899; and US Pat. No. 4,367,924).
It is based on the principle of C technology.

[0003] Other conditions of the S _c * phase used in this type of ferroelectric display are as follows. (1) The S _c * phase must be present in the widest possible temperature range around ambient temperature. (2) The liquid crystal medium compound forming the S _c * phase must be chemically stable and pure. (3) For example, spontaneous polarization (P), optical anisotropy (△
n), fluid viscosity (μ), dielectric anisotropy (△ ε), tilt angle (θ), pitch (p), and other physical property parameters of the liquid crystal must take optimal values.

[0004] In the case of Nematchiku (N) phase or S _A phase,
The range of the phase is usually the moderate phase transition temperature T _NI or T
Expanded by preparing a mixture of various N or S _A phase components with _SA-I , often having a lower melting point than the average melting point. The S _B phase is often induced in the S _C phase mixture or the S _A phase in which the S _C phase predominates
This process cannot be easily transitioned to the S _C phase, as it is restricted to a narrow temperature range by the phase. further,
The range of materials with a broad phase range _Sc phase and distinguished from others in terms of high chemical stability and purity is significantly smaller than the pool of nematic compounds. As a result, the mixing possibilities are severely limited.

Therefore, the demand for providing an S _c phase satisfying the conditions (1) and (2) is not trivial, and the problem of simultaneously satisfying the conditions (1) to (3) is substantially unsolved. Can be considered.

Thus, in order to provide a liquid crystal medium having an S _c phase, the liquid crystal component which does not necessarily include the S _c phase is covered by the widest possible range of liquid crystal components, and the conditions (1) to (3)
There is considerable demand for a mixing concept that significantly extends the range of simultaneously satisfying

In known ferroelectric liquid crystal displays, a liquid crystal medium having a spontaneous polarization generally exceeding 10 nC / cm ² is used. The following formula

[0008]

(Equation 1) (Where γ is the viscosity, P is the spontaneous polarization, and E is the electric field), because the switching time becomes shorter as the spontaneous polarization increases.

[0009]

It is an object of the present invention to provide a new ferroelectric liquid crystal display with improved multiplex performance.

[0010]

Surprisingly, it has now been found that this object is achieved by providing a liquid crystal display according to the invention.

The present invention relates to a ferroelectric liquid crystal medium, ie, one or more chiral dopes, between two plane-parallel plates with a sampling electrode and an electrode matrix of data electrodes arranged at right angles thereto. A chiral component and a non-chiral base component composed of one or more non-chiral compounds.
A ferroelectric liquid crystal display comprising a medium having a dielectric anisotropy of 2 and a spontaneous polarization of less than 8 nC / cm ² and having improved multiplex performance. In particular, the non-chiral substrate component comprises the components 2-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, thia-
It relates to a liquid crystal display of the type comprising at least one compound comprising 3,4-diazole-2,5-diyl or 1-cyano-1,4-cyclohexylene.

Further preferred is a liquid crystal display in which the above-mentioned non-chiral substrate component basically comprises the compounds represented by the following components I and II.

[0013]

Embedded image Wherein n and m are each independently 5 to 12, X is N or CH and L ¹ and L
² is H or F but at least one ligand L ¹
Or L ² is different from H, and Z ¹ and Z ² are-
O- or a single bond.

In particular, component I comprises one or more compounds of the formulas Ia, Ib, Ic and Id:

[0015]

Embedded image Preferred are liquid crystal displays wherein component II comprises one or more compounds of the following formulas IIa to IIi.

[0016]

Embedded image A liquid crystal display in which the non-chiral base component contains 35% or more of compound I and 8 to 50% of compound II by weight is more preferable.

The weight ratio of the chiral compound is 1 to 25.
%, And more preferably a liquid crystal display in which the chiral compound comprises one or more compounds represented by the following formula III.

C _n H _{2n + 1} -QABQ ¹ -C * -R ° Y-Q ² -C _m H _{2m + 1} III In the formula, n and m are each independently 2 to 12, Q represents -O- or a single bond, and -AB-
Represents a group represented by the following formula or an enantiomer of these groups.

[0019]

Embedded image Wherein each L is independently H or F;
Is CH or N. Q ¹ and Q ² are each independently —COO—, —O— or an alkylene group having 2 to 4 carbon atoms (where one CH ₂ group in the group is —O—
-, -S-, -CO-, -O-CO-, -CO-O-,
-S-CO-, -CO-S-, -CH = CH-COO
-, -CH = CH-, CH halogen- and / or-
CHCN-), or each is a single bond (here, Q ¹ is -O-, -CH ₂ CH ₂
- or -OCH ₂ - is, Q ² is -COO- or a single bond is preferred), Y is halogen, CN, CH _3,
CH ₂ CN or OCH ₃ , preferably F or CH ₃ , and R ° is H or an alkyl group having 1 to 10 carbon atoms different from Y and —Q ² -C _m H _{2m + 1} But preferably H, and C * is a carbon atom bonded to four different substituents.

The liquid crystal mixture preferably has a spontaneous polarization of more than 1 nC / cm ² .

Further, it is preferable that the liquid crystal mixture contains at least one chiral dope. This chiral dope preferably has a spontaneous polarization exceeding 5 nC / cm ² . This liquid crystal mixture preferably has a slightly negative dielectric constant (△ ε) anisotropy. This is from -0.01 to-
1.1, particularly preferably in the range of -0.1 to -1.

The physical property parameters Δε and P are shown at room temperature. At higher or lower temperatures these parameters vary according to the temperature coefficient.

The smectic phase is classified according to the structure observed under a polarizing microscope, and is known as A, B, C... Type smectic phase. All types of smectic phases have a parallel orientation of the molecules in the layer, but the types of orientation vary.

A difference is observed between the orthogonal smectic phase and the inclined smectic phase. In the orthogonal structure, the long axis of the molecule is oriented perpendicular to the layer plane on average, but the molecule on the inclined phase is inclined by the tilt angle with respect to the long axis plane on average. The chiral gradient phases exhibit ferroelectricity, indicating that they are important for SSFLC displays.

In the two orthogonal S _A and S _B phases, the interlayer distance approximately corresponds to the length of the liquid crystal molecules. The S _A phase, the molecules are significantly higher degree of freedom in the layer with respect to rotation of the displacement and rotation of the vertical axis of the molecule. This relatively loose molecular composition means that the molecular layer is quite flexible. In contrast, since molecules with the orthogonal S _B phase is placed close-packed hexagonal in the layer, this phase can be said to be a smectic phase arranged more order.

In the graded smectic phase, the interlayer distance is on average less than the length of the liquid crystal molecules. An example of a gradient smectic phase is S in which the orientation of molecules in the layer is relatively small.
_c phase, S _I and S _F phases of a liquid crystalline smectic phase having a higher order orientation, and S _{G of} a crystalline smectic phase,
S _H, include S _K and S _J.

Higher ordered smectic phases are generally characterized in that they correlate with the molecular centroid in addition to the arrangement of the molecules in the layer.

Since the chiral gradient smectic phase is ferroelectric, it can be used as a liquid crystal medium in SSFLC displays. Among the liquid crystalline gradient chiral smectic phases, the S _c * phase is the most suitable and has been most often used in displays manufactured to date.

The constituent 2,3-difluoro-1,4-
Compounds containing phenylene, although it is preferred to have the S _c phase, it is also possible to use this type of compound having no S _c phase.

The preparation of compounds containing this component is described, for example, in DE-A-3807801, DE-A-38.
No. 07823, German Patent No. 3807803, German Patent No. 3807870, German Patent No. 3807819
, German Patent No. 3807861, German Patent No. 38
No. 07871, DE-A-3807802 and DE-A-3807682. Modifications that are known per se may be used,
The details are not described here. If necessary, without the starting material being formed in situ and isolated from the reaction mixture,
The target compounds can also be produced by directly reacting them.

The compound of the non-chiral base material component containing the component 2-fluoro-phenylene or 2,3-difluoro-1,4-phenylene is preferably a compound represented by the following formula A.

[0032]

Embedded image In the formula, R ¹ and R ² are each independently an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 3 to 15 carbon atoms, each of which is unsubstituted, monosubstituted with a cyano group, Or at least monosubstituted by fluorine or chlorine, but in each case one CH ₂ group in these groups is —O—, —S—, —CO—, —O—CO
It may be substituted by-, -CO-O- or -O-CO-O-. One of these R ¹ and R ² groups may be a chirality-derived organic radical Q * containing an asymmetric carbon atom. A ¹ and A ² are each independently unsubstituted or substituted with one or two F and / or one Cl and / or CH ₃ and / or CN groups, and One or two CH groups are 1,4-phenylene groups which may be substituted with N, or one or two non-adjacent CH ₂ groups in the group are O atoms and / or S atoms, respectively. Or piperidine-1,4-
Diyl, 1,4-bicyclo (2,2,2) -octylene, 1,3,4-thiadiazole-2,5-diyl, naphthalene-2,6-diyl or 1,2,3,4-tetrahydronaphthalene- Represents a 1,4-cyclohexylene group which may be substituted by 2,6-diyl, wherein Z ¹ and Z ² are each independently -CO-O-, -O-CO
_{-, - CH 2 CH 2 -} , - OCH 2 -, - CH 2 O -, - C
≡C- or a single bond; X represents H or F;
m and n are each 0, 1 or 2;
(M + n) is 1 or 2.

Compounds of formula A include bicyclic and tricyclic 2-
Fluoro- and 2,3-difluoro-1,4-phenylene derivatives are included. Bicyclic compounds are preferred, in which R ¹ has 5 to 12 carbon atoms, especially 7 to 10 carbon atoms.
The compound which is an n-alkyl or n-alkoxy group is preferable.

Further, in the tricyclic compound of the formula A, m = n = 1
Alternatively, it is preferable that m = 0 and n = 2.

Preferred compounds of the formula A are described in DE-A-3807801, DE-A-3807823
, German Patent No. 3807803, German Patent No. 38
No. 07870, German Patent No. 3,807,819, German Patent No. 3,807,861 and German Patent No. 3,807,871
And German Patent No. 3,807,802.

R ¹ and R ² are each independently alkyl, alkoxy, alkanoyl, alkanoyloxy,
Preference is given to alkoxycarbonyl or alkoxycarbonyloxy, in each case having 5 to 1 carbon atoms.
2, particularly preferably 6 to 10. Alkyl and alkoxy are particularly preferred. Preferably, one of R ¹ and R ² is alkyl. A particularly preferred combination is the case where R ¹ = alkyl and R ² = alkoxy, and the case where R ¹ = alkoxy and R ² = alkyl. R ¹ and R ² containing straight-chain alkyl are particularly preferred.

R ¹ is n-alkyl having 5 to 13 carbon atoms and R ² is n-alkyl, n-alkoxy, n-alkanoyloxy, n-alkoxycarbonyl or n-alkylthio having 5 to 11 carbon atoms. Certain compounds of formula A are more preferred.

Further preferred are compounds of formula A as chiral component, wherein ^one of the R ¹ and R ² groups is a chiral group of formula B:

-Q ¹ -C * -R ° X-Q ² -R ² B In the formula, Q ¹ and Q ² each independently represent one CH ₂ group of —O—, —S— , -CO-, -O-CO-,
-CO-O-, -S-CO-, -CO-S-, -CH =
CH-COO-, -CH = CH-, CH halogen- and / or -CHCN- which may be substituted with alkylene having 2 to 4 carbon atoms or a single bond, and X represents halogen, CN, CH ₃ , CH ₂ CN or O
CH ₃ and R ° is H, or Y and —Q ² —R ²
Is an alkyl group having 1 to 10 carbon atoms, and C * is a carbon atom bonded to 4 different substituents.

Compounds of the formula I containing radicals II of this type are represented by 1
By using more than one, a liquid crystal medium of the present invention having a ferroelectric chiral S _c * phase is obtained.

Q ¹ in the formula B is preferably C 2-4 n-alkyl, n-alkoxy, n-alkanoyloxy or n-alkoxycarbonyl. Furthermore, Q ¹ Wherein Y is F, Cl, CN or H, and W is-
CH ₂ — or a single bond.

X in the formula B is halogen, CN, OCH ₃
Or CH ₃ , especially F, Cl, CN, OCH ₃ or CH
₃ and even more preferably CH ₃ .

R ° in formula B is H, n-alkyl, n-alkoxy having 1 to 3 carbon atoms, especially H, CH ₃ , CH
Most preferably, it is ₃ O and further H.

Q ² -R ² in the formula B is preferably n-alkyl, n-alkoxy having 1 to 5 carbon atoms, particularly n-alkoxy having 1 to 3 carbon atoms.

The non-chiral component has the formula I, in particular X
Is N, 60 to 100% by weight, in particular 65 to 80% by weight, of one, two, three or more compounds
Particularly preferred are ferroelectric liquid crystal displays comprising a liquid crystal medium.

In addition, the non-chiral component may comprise from 0 to 40% by weight, in particular from 20 to 40% by weight of one, two, three or more compounds of the formula II, in particular where L ¹ and L ² are F,
It is particularly preferred that the content be from 30 to 30 wt%.

The non-chiral component has the constituent 2-fluoro-
Without 1,4-phenylene, 2,3-difluoro-1,4-phenylene or 1-cyano-1,4-cyclohexylene, the chiral component comprises at least one compound comprising one of these components. It is a thing.

Since the switching time τ of an SSFLC display is inversely proportional to the spontaneous polarization P, the liquid crystal mixtures according to the invention having a high spontaneous polarization are preferred. P is 1 nC / cm ²
Values exceeding 5 nC / cm ² , especially values between 6 and 8 nC / cm ² , are very preferred.

The liquid crystal medium used in the liquid crystal display of the present invention must be ferroelectric. This can include one or more components of the liquid crystal medium having a single chiral center, and / or one or more chiral dopants S _c
Achieved by adding to the base medium. This dope may be mesogenic or non-mesogenic, but in the latter case it is preferred to have a structure similar to liquid crystal molecules. It is preferable to use a chiral dope with a high spontaneous polarization P. Thereby, the spontaneous polarization is modified substantially independently of other properties of the medium, such as phase range, viscosity and the like. A chiral dope having a spontaneous polarization P of more than 10 nC / cm ² is preferable.

A liquid crystal display with multiplex performance based on the principle of SSFLC technology is preferred. In these systems, the smectic layer is oriented perpendicular to the cell plane. The helical arrangement in the tilt direction of the molecules is suppressed by making the distance between the plates very small (about 1-2 μm). This aligns the long axis of the molecule in a plane parallel to the cell plane, resulting in two preferred tilt directions. By applying a suitable alternating electric field, switching can be switched between these two states of the liquid crystal phase with spontaneous polarization. This switching drive is significantly faster than in a conventional twisted cell (TN-LCD) based on a nematic liquid crystal.

Such a ferroelectric liquid crystal display having multiplex performance is described in, for example, S. Shimoda et al.
Proceedings of SID, Vol. 28/2, 1987, 201-204, and EP 0 366 117, EP 036753
No. 1, EP 0370649 and EP 0
No. 374865.

[0052] Further, the liquid crystal display of the present invention that the liquid crystal polymer composition comprising a low molecular weight liquid crystal medium having a ferroelectric liquid crystal polymer and the S _c phase or S _c * phase is preferably used. A similar electro-optical system is described, for example, in EP 0297554.

The display according to the invention is manufactured by a method known per se. In general, these compounds have the property of being mutually soluble at high temperatures and the liquid-crystalline medium is incorporated into the display in a manner known per se, for example as described in K. Iwasa JEE, September 1986, 33-37. be introduced.

The following examples are intended to illustrate, but not limit, the invention. Above and below, percentages are given in weight percent and all temperatures are given in degrees Celsius.

The ferroelectric liquid crystal display used in the following embodiments has the following driving method (see FIG. 1). A: Ideal “bipolar phase” B and C: S. Shimoda et al., Proceedings of SID, Vol.
D and E: T. Umeda et al., Japanese Journal of Applied
In the two comparative examples (FIGS. 6, 7 and 8), a decrease in contrast ratio is clearly observed in the AC electric field stabilization matrix driving method as described in Physics 27 (7) 1988, 1115-1121. Further, in these liquid crystal displays, the range of the pulse width of the driving methods B to E is significantly reduced.

The following compounds were used in the liquid crystal mixture.

[0057]

Embedded image

[0058]

EXAMPLES Example 1 Liquid Crystal Medium A liquid crystal medium having the following composition was produced.

% By weight 31.66 PYP-9.09 31.66 PYP-9.09 31.66 PYP-9.07 and 5.00 NCB-7.08 F * phase sequence: S _c * 65S _A 73Ch74I △ ε = −0.07, P = 5.5 nC / cm ^{2 A} ferroelectric liquid crystal display containing this medium has high multiplex performance (see FIGS. 2 and 3). Example 2: Liquid crystal medium A liquid crystal medium having the following composition was produced.

Weight% 23.75 PYP-9.09 23.75 PYP-9.08 23.75 PYP-9.07 7.916 PYP-9.09 FF 7.916 PYP-9.08 FF 7.916 PYP-9.07 FF 5.00 NCB-7.08 F * phase arrangement: S _c * 65SA68Ch70I Δε = -0.9, P = 7.0 nC / cm ² The ferroelectric liquid crystal display containing this medium is: High multiplex performance (see FIGS. 4 and 5). Comparative Example 1 Liquid Crystal Medium A liquid crystal medium having the following composition was produced.

% By weight 15.8 PYP-9.09 15.8 PYP-9.08 15.8 PYP-9.07 15.8 PYP-9.09 FF 15.8 PYP-9.08 FF 15.8 PYP-9.07 FF 5.00 NCB-7.08 F * Phase arrangement: S _c * 63S _A 64Ch65I Δε = -1.8, P = 8.0 nC / cm ² Ferroelectric liquid crystal display containing this medium Has low multiplex performance (see FIGS. 6 and 7). Comparative Example 2: Liquid crystal medium A liquid crystal medium having the following composition was produced.

% By weight 21.25 PYP-9.09 21.25 PYP-9.08 21.25 PYP-9.07 7.08 PYP-9.09 FF 7.08 PYP-9.08 FF 7.08 PYP-9.07 FF 15.00 NCB-7.08 F * Phase arrangement: S _c * 68S _A 71Ch74I Δε = -1.25, P = 20.0 nC / cm ² Ferroelectric liquid crystal display containing this medium Has low multiplex performance (see FIG. 8).

[Brief description of the drawings]

1 is a schematic diagram showing the ratio of the AC stabilized voltage V _AC and the frequency f _s of the signal ratio between the frequency of the alternating electric field f _AC, and the signal voltage V _s.

2 is a graph showing the contrast ratio (between a written pixel and a non-written pixel) as a function of the pulse width (μs) of the liquid crystal medium of Example 1 for various driving methods A to C. FIG.

FIG. 3 is a graph showing the contrast ratio (between a written pixel and a non-written pixel) as a function of the pulse width (μs) of the liquid crystal medium of Example 1 for various driving methods A, D and E. .

FIG. 4 is a graph showing the contrast ratio as a function of the pulse width of the liquid crystal medium of Example 2 for various driving methods A to C.

FIG. 5 is a graph showing the contrast ratio as a function of the pulse width of the liquid crystal medium of Example 2 for various driving methods A, D and E.

FIG. 6 is a graph showing the contrast ratio as a function of the pulse width of the liquid crystal medium of Comparative Example 1 for various driving methods A to C.

FIG. 7 is a graph showing the contrast ratio as a function of the pulse width of the liquid crystal medium of Comparative Example 1 for various driving methods A, D and E.

FIG. 8 is a graph showing the contrast ratio as a function of the pulse width of the liquid crystal medium of Comparative Example 2 for various driving methods A to C.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Axel Pausch, Germany D-6100 Darmstadt Frankfurter Straße 250 (72) Inventor Michael Compter Der Germany D-6100 Darm Stadt Frankfurter Straße 250 ( 72) Inventor Bernhard Scheuble, Germany D-6100 Darmstadt Frankfurter Straße 250 (56) References JP-A-62-240378 (JP, A) JP-A-63-192021 (JP, A) JP 2-189386 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/141 C09K 19/58

Claims (11)

(57) [Claims] 1. A ferroelectric liquid crystal medium between two plane-parallel plates provided with an electrode matrix of a sampling electrode and a data electrode perpendicular thereto, namely a chiral component comprising one or more chiral dopes and one or more chiral components. A medium comprising a non-chiral base component comprising a non-chiral compound, wherein the medium has a dielectric anisotropy of -0.01 to -1.2 and a spontaneous polarization of less than 8 nC / cm ² (electrostatic anisotropy) (The spontaneous polarization data is based on room temperature.) How to improve the multiplex performance of ferroelectric static liquid crystal displays. 2. The composition of claim 2, wherein said non-chiral substrate component comprises
-Fluoro-1,4-phenylene, thia-3,4-diazole-2,5-diyl, 2,3-difluoro-1,4
The method according to claim 1, characterized in that it comprises at least one compound comprising -phenylene or 1-cyano-1,4-cyclohexylene. 3. The composition of claim 1, wherein said non-chiral substrate component is
And II Wherein n and m are each independently 5 to 12
X is N or CH; L ¹ and L ² are H or F, but at least one ligand L ¹ or L ² is different from H; Z ¹ and Z ² Is -O- or a single bond]. The method according to claim 1 or 2, wherein 4. The compound of claim 1, wherein said component I is of one or more of formulas Ia, Ib, Ic and Id: The method of claim 3, comprising: 5. The composition of claim 2, wherein said component II is of the formula IIa to IIi:
One or more compounds of the formula The method according to claim 3, comprising: 6. The non-chiral base material component comprises compound I and compound II in a weight ratio of I ≧ 35% II = 8 to 50%.
The method according to any one of claims 1 to 4. 7. The method according to claim 3, wherein the weight ratio of the chiral compound is 1 to 25%. 8. The chiral compound represented by the following formula III: C _n H _{2n + 1} -QABCB ¹ -C * -R ° Y-Q ² -C _m H _{2m + 1} III wherein n And m are each independently 2 to 12
And Q is -O- or a single bond, and -AB-
Is the following formula: Or enantiomers of these groups, wherein each L is independently H or F, and X is CH or N.
Q ¹ and Q ² are each independently -COO-, -O-
Or an alkylene group having 2 to 4 carbon atoms (where one CH ₂ group in the group is —O—, —S—, —CO—, —O
-CO-, -CO-O-, -S-CO-, -CO-S
-, -CH = CH-COO-, -CH = CH-, CH halogen- and / or -CHCN-) or a single bond, and Y is halogen, CN, CH ₃ , CH ₂ CN or OCH
Is _3, R ° is H or an alkyl group of from 10 1 to different carbon atoms and Y and _{^{-Q 2 -C m H 2m + 1}} , preferably H, C * is four A carbon atom bonded to a different substituent.]. 9. The method according to claim 9, wherein Q ¹ represents —O—, —CH ₂ CH ₂ — or —OCH ₂ —, Y is F or CH ₃ , R ゜ is H, and Q ² is —COO— or 9. The method according to claim 8, wherein the compound is a single bond and m is 2 to 8. 10. A ferroelectric liquid crystal medium between two plane-parallel plates with an electrode matrix of a sampling electrode and a data electrode perpendicular thereto, ie a chiral component comprising one or more chiral dopes and one or more chiral components. A medium comprising a non-chiral base component comprising a non-chiral compound, wherein the medium has a dielectric anisotropy of -0.01 to -1.2 and a spontaneous polarization of less than 8 nC / cm ² (electrostatic anisotropy) And the spontaneous polarization data is based on room temperature) ferroelectric static liquid crystal display with improved multiplex performance, wherein the non-chiral substrate component has at least one formula A [Wherein, R ¹ and R ² are each independently an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 3 to 15 carbon atoms, each of which is unsubstituted, monosubstituted with a cyano group, Or at least one mono-substituted with fluorine or chlorine, in each case one C in these groups
H ₂ group is —O—, —S—, —CO—, —O—CO—,
—CO—O— or —O—CO—O—, and ^one of R ¹ and R ² may be a chirality-derived organic group Q ^* containing an asymmetric carbon atom. A ¹ and A ² are each independently unsubstituted or substituted with one or two F and / or Cl atoms and / or CH ₃ and / or CN groups; Or 2
CH groups are 1,4-phenylene groups which may be substituted by N, or one or two non-adjacent CH ₂ groups, respectively.
The group is O atom and / or S atom, or piperidine-1,4
-Diyl, 1,4-bicyclo (2,2,2) -octylene, 1,3,4-thiadiazole-2,5-diyl, or 1,2,3,4-tetrahydronaphthalene-2,6-
Represents a 1,4-cyclohexylene group which may be substituted with diyl; Z ¹ and Z ² each independently represent -CO-O-, -OC
_{O -, - CH 2 CH 2} -, - OCH 2 -, - CH 2 O -, -
X represents H or F, m and n are each 0, 1 or 2, and (m + n) is 1 or 2]. Characteristic ferroelectric liquid crystal display. 11. The non-chiral substrate component is essentially the following components I and II: Wherein n and m are each independently 5 to 12
X is N or CH; L ¹ and L ² are H or F, but at least one ligand L ¹ or L ² is different from H; Z ¹ and Z ² Is -O- or a single bond.] The liquid crystal display according to claim 10, wherein